School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China.
School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China.
Sci Total Environ. 2021 Jul 10;777:146123. doi: 10.1016/j.scitotenv.2021.146123. Epub 2021 Mar 1.
The aluminum dross (AD), which causes numerous problems of its management and disposal to environment is a useful resource to extract alumina. This study explains a novel process to extract highly pure alumina (AlO) from AD at a high extraction rate without producing the residues and exhaust gases. An experimental set up was designed to perform the grinding of AD for the decomposition of aluminum nitride (AlN) and the removal of salts. Thereby, the desalted dross was used to detect the optimum alkaline (NaOH) calcination parameters and leaching conditions, as well as the dissolution kinetics of alumina and silica. The leaching residues were used to produce Ettringite mineral with calcium-based compounds (including CaO and CaSO) to avoid the problems of solid waste disposal from the leaching process. Moreover, to purify the alumina, slightly soluble CaSO was added in leaching solution to precipitate silicate and the optimum additive/solution ratio (g/mL) was determined. The aluminum hydroxide (Al(OH)), precipitated after the carbonization was calcinated at 900.0 °C for 2 h to produce γ-alumina. The morphological and mineralogical characterizations of AD, γ-AlO and the synthesized Ettringite mineral were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and X-ray fluorescence (XRF). It was observed that activation temperature of 1000.0 °C, NaO/AlO molar ratio of 1.4, leaching temperature of 60.0 °C, leaching time of 40.0 min, and the leaching liquid/solid ratio (mL/g) of 25/1 were the optimal parameter conditions to extract alumina with the extraction rate at 86.7% and purity of more than 98%. The results of leaching kinetics' study showed that the dissolution of alumina and silica were both controlled by layer diffusion process with the apparent activation energy of 11.4010 kJ·mol and 2.0556 kJ·mol, respectively.
铝渣（AD）是一种有用的资源，可以从中提取氧化铝，但它在管理和处置方面给环境带来了诸多问题。本研究解释了一种从 AD 中以高提取率提取高纯度氧化铝（AlO）的新工艺，该工艺在不产生残渣和废气的情况下进行。设计了一个实验装置来进行 AD 的研磨，以分解氮化铝（AlN）并去除盐。由此，对脱盐后的铝渣进行了最佳碱性（NaOH）煅烧参数和浸出条件，以及氧化铝和二氧化硅的溶解动力学的检测。浸出残渣被用于与基于钙的化合物（包括 CaO 和 CaSO）生产钙矾石矿物，以避免浸出过程中固废处理的问题。此外，为了净化氧化铝，在浸出溶液中加入微溶性 CaSO 以沉淀硅酸盐，并确定了最佳添加剂/溶液比（g/mL）。碳化后沉淀的氢氧化铝（Al(OH)）在 900.0°C 下煅烧 2 小时，生成 γ-氧化铝。通过 X 射线衍射（XRD）、场发射扫描电子显微镜（FESEM）和 X 射线荧光（XRF）研究了 AD、γ-AlO 和合成的钙矾石矿物的形貌和矿物特性。结果表明，在 1000.0°C 的活化温度、1.4 的 NaO/AlO 摩尔比、60.0°C 的浸出温度、40.0 分钟的浸出时间和 25/1 的浸出液/固比（mL/g）下，氧化铝的提取率为 86.7%，纯度超过 98%，是提取氧化铝的最佳参数条件。浸出动力学研究结果表明，氧化铝和二氧化硅的溶解均受层扩散过程控制，表观活化能分别为 11.4010 kJ·mol 和 2.0556 kJ·mol。
